I have apparently managed to grow large numbers of Cannas outside, for a few years, and managed to take large numbers of photos of them, without ever showing you those pictures in a post here at PATSP. How did this happen? It is a mystery. (Weirder still: I appear to have deleted most of the photos I've taken, so I don't have that much to show you even now.) But since the subject's come up:
As best as I can remember, I got the first Canna rhizomes in 2010, from a friend in town, and we planted them in the spring of 2011. Since then, every year we dig them all up in October, store them in the basement for the winter (probably too warm, but the best we have, and they don't seem to mind too much), and then plant them outside again in May. I then spend a couple months trying and failing to keep them weeded, until they get big enough to block light from competing plants and become essentially self-weeding. In July, they start to bloom. In August, I see a hummingbird. Also in August, I start collecting seeds from them. And then it's October, and the Circle of Cannas begins all over again.
Before 2015, we've always planted all the Cannas we had in a bed along the north edge of our property (the "fence bed"), as in the first photo, above; in 2015, we found we had so many of them that they wouldn't all fit there, so two new beds were created. We put one of the new beds along the far west edge of the property (the "west bed"), where they sort of blocked the view of the cornfield. (Ordinarily, this would have made me mildly unhappy, because I like the cornfield, but 2015 was a soybean year, and soybeans can blow me.) The other new bed was
The west bed has never really seemed to reach its full potential in terms of growing the biggest, baddest Cannas possible, but it was interesting anyway, in that it more or less turned into a living graph:
The left side of that row is right under the neighbors' maple tree, so the plants there get more shade than the ones on the right end. There's also probably something of a rain-shadow effect going, since the maple hangs way over the fence. I suspect that the rain is the more relevant problem, since the square bed is also in shade for most of the day and got a lot taller: it was close enough to the house that we occasionally watered it ourselves, and it didn't have a tree overhanging it and stealing its water.
There doesn't seem to be a lot of enthusiasm for Cannas in Iowa, from what I can tell. Nobody seems to have very many, and there are two main ways I see them used around here: 1) in a row, to hide a fence or cover the side of a building, and 2) as The Tall Thing in a group container. Maybe if they were winter-hardy here and one didn't have to dig them up every fall and re-plant them every spring, people would use them in regular gardens more often. Or maybe it's that (digging/replanting aside) they're too easy to grow, so Iowa gardeners just don't respect them. (Maybe just gardeners in general: DCTropics recently wrote a Canna-celebratory post that nevertheless characterized them as being for lazy gardeners.1)
We have sometimes had bug problems: 2015 was terrible for Japanese beetles. I dumped hundreds of them into jars of soapy water, for weeks, and never felt like I was even making a dent in the overall population.
And there was one year (I think 2010) with incredible whitefly swarms: some years I don't see any, most years I see a few, but that one year was like a never-ending snowstorm.
Candy-striped leafhoppers (Graphocephala coccinea) hang out on them from time to time, but don't seem to be causing the plants any serious problems, and they're never in huge swarms. We've had quite a few grasshoppers in 2015 after the Japanese beetles left, but they didn't seem interested in eating the Cannas; they just liked to hang out on them after they finished eating other plants (mostly Iris).
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In 2015, for the first time, the Cannas also attracted remarkable numbers of spiders, of a species I wasn't previously familiar with and couldn't identify even after a good hour of online searches.
My best guess is Neoscona crucifera, which is at least hairy, known to live in Iowa, and a builder of vertical, orb-shaped webs. Still uncertain because N. crucifera is supposed to be nocturnal, and these didn't appear to be (I saw them both hiding and out in the middle of their webs during the day; they didn't seem to have a strong time-of-day preference), and because the ones on my Cannas had a consistent, distinctive, and vaguely octopus-/Cthulhu-looking way of folding their legs up over their heads, whereas the photos of N. crucifera on-line frequently show them with all legs stretched out wide.
Whatever they were, there were a lot of them.
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My personal dream for the back yard, which the husband is aware of but not particularly enthusiastic about,2 is that we replace the lawn in much of the back of the yard with a meandering path, with Cannas on either side. (If we had more yard, I'd want a Canna maze, but the property is too long and narrow for that. Also this year's experience with the west bed suggests that we couldn't count on the Cannas reaching a uniform height, which would ruin the maze effect.) I intend to try to sell the meandering-path idea hard this winter as a "but think how much less lawn-mowing you'd have to do,"3 and we'll see if that works. If not, I suppose I can encourage the incremental expansion of the existing beds until we reach full lawn-replacement.4
2 (because he's the one who would actually have to plant it and dig it up)
3 (The husband does the lawn-mowing too. I'm not actually opposed to lawn-mowing or Canna-digging, but I overheat too quickly to be much good at either. I mostly handle the weeding and the strawberry-picking, though, so it sort of balances out.)